Chapter 1. Chapter 32: Plant Physiology

1.1 Introduction

Welcome to the Interactive Study Guide for Chapter 32: Plant Physiology! This Study Guide will help you master your understanding of the chapter's Driving Questions, using interactive Infographics and activities, as well as targeted assessment questions. Click "Next" to get started, or select a Driving Question from the drop-down menu to the right.

DRIVING QUESTIONS

• How is a plant body structured, and how do plants obtain water and grow?
• How do plants obtain nutrients?
• How do plants reproduce, respond to stimuli, and protect themselves?

1.2 Driving Question 1:

Why should you care?

For many, it's hard to care about plants because they are so different from us and because they appear so stationary. It may be surprising to think of plants as having a physiology, since they seem so inert. You have already learned that plants are the basis of the terrestrial food webs, including the food web that feeds humans. Understanding how these important organisms work will help you appreciate their significance to your daily life.

What should you know?

To fully answer this Driving Question, you should be able to:

1. List and describe the function of most common parts of the root system and shoot system in plants.
2. List and describe the function of most common parts of plant cells.
3. Compare and contrast xylem and phloem.
4. Explain how transpiration works.

Infographic Focus

The Infographics most pertinent to the Driving Question are 32.1 and 32.2.

1.3 Driving Question 2:

Why should you care?

As you've read many times by now, it is important that plants undergo photosynthesis so that life can exist on Earth. All of the energy you get from food was originally captured by plants—even if you rarely eat them. Except for mineral supplements and mineral-fortified foods, all of the elements in your body were once part of a plant. Many of the vitamins and other essential molecules we need are made by plants as well. Plants have many strategies to capture these nutrients and energy, and understanding and appreciating how they do this may prevent you from skipping that salad at dinner.

What should you know?

To fully answer this Driving Question, you should be able to:

1. Explain the strategies plants use to obtain nutrients from their environment.
2. Explain the dilemma faced by plants in hot, arid climates.
3. Explain strategies used by plants to conserve water.

Infographic Focus

The Infographics most pertinent to the Driving Question are 32.3 to 32.5.

1.4 Driving Question 3:

Why should you care?

Most people think of flowers in terms of what they symbolize: love, mourning, beauty. In an arrangement or on a parade float, they become simple splashes of color. For plants, flowers mean sex. A flower is an efficient device to facilitate sex in plants, usually by attracting animals to help transfer gametes for them. Flowers and sexual reproduction in plants have given rise to the amazing diversity of plants on the planet, which makes all our lives richer.

Like flowers, seeds have long been symbols, usually of beginnings; this is perhaps a more apt comparison. Seeds are analogous in many respects to eggs: they have a protective covering that contains a developing embryo and an energy source for its development. Unlike the eggs of most animals, seeds are meant to be dispersed away from the parents, and there are several methods plants use for seed dispersal.

Although plants do not have nerves or think in any way analogous to the way we do, they do sense their environment and respond to it, sometimes with surprising speed. By learning about how plants react to their environment you will begin to see plants more as active organisms and less as inert objects.

Plants use a variety of physical and chemical defenses to prevent being eaten or otherwise bothered. Some plants even employ animals for protection. For example, some tropical trees provide shelter and nectar in swollen parts of their stems to ants in exchange for them biting or stinging any other animal, thus warding off would-be predators. Plant defense strategies may have shaped the development of agriculture. Some scholars point out that humans have tended to domesticate vegetable crops that are either poisonous or otherwise inedible without processing. For example, broccoli, cabbage, and other similar mustard-family vegetables produce chemicals that are poisonous or distasteful to most insects but not to us. Artichokes are actually giant thistles, covered with prickles that make them inedible without use of a knife. Cassava, the main starch vegetable for most of the tropical world, naturally has toxic levels of cyanide until processed properly. We have also benefited from some plants’ chemical defenses, which are useful as medicines.

What should you know?

To fully answer this Driving Question, you should be able to:

1. Identify the parts of a flower used in sexual reproduction.
2. Explain the events that take place during pollination.
3. Explain the basic features and functions of seeds and which members of the plant kingdom produce them.
4. Describe some of the seed dispersal methods plants use.
5. Explain how the hormone auxin is used in a plant's response to light, gravity, and physical contact.
6. Explain how plants evade predation.

Infographic Focus

The Infographics most pertinent to the Driving Question are 32.6 to 32.11.